Today's optical libraries have low performance, with access times of 10s of seconds to a minute or more. While optical drives allow fast random access to data on a disc, the overall random access performance is limited by the media move time and drive initialization times. The latter limitations means that today's optical systems are largely designed for slow tier operations. Additionally, cloud environments require the library to provide high performance and high reliability at very large scales. Service level agreements need to be maintained in the face of various component failures, including concurrent loss of a storage unit, loss of a piece of media in a further storage unit and loss of a block of data from a further piece of media.